[Coco] Need new disk drive...

[Joel Ewy]

Phill Harvey-Smith wrote:
> Michael Robinson wrote:
>> My 360k drives are faulty.  I looked on ebay, all I could find were DSDD
>> drives.  I can't use DSDD drives can I?  
> ...
> Something else to considder, unless you have a whole bunch of 5.25"
> disks, is that it's perfectly possible to use standard PC 1.44M 3.5"
> drives with the correct cable, as long as you always use 720K media.
>
I've been using 1.44M 3.5" drives on my CoCo for 12 years or more.  If
you can still find 720K disks they work great for copying data and disk
images from modern PCs.  I sometimes get boxes of old, used floppy
disks, mostly HD, but peppered here and there with 720K disks that can
be re-formatted.  I often see them sitting on shelves collecting dust at
places where I do computer work.  More often than not, no current
employee can even remember the last time they were used and they're mine
for the asking.

I recently took home a large box of floppy disks (along with hundreds of
pounds of discarded computer equipment from a Tandy 1000HX to G3 iMacs
to Athlon XP 2000+ motherboards) from my old college.  In the box I
found 6 or 8 low density 3.5" disks formatted to 800K for Macintosh,
about as many 720K DOS disks, and about 8 that appear never to have been
formatted.

Sometimes CD-ROM and other device drivers came on 720K disks.  I have
one here that has a Flash ROM utility for an old Pentium motherboard. 
It looks like the label will peel up pretty easily, so I plan on
transferring the contents to a HD floppy and using the 720K disk on a
classic computer like the Amiga or CoCo where it can do some real good. 
The 720K disks are pretty easy to pick out among 1.44M disks because
they have only the write-protect hole on the top.

With a patched disk ROM or a few POKEs you can format and use the back
side, and in OS-9 they format to 720K, which is really nice.  I've
always wondered how hard it would be to patch Disk BASIC to add a fixed
track offset for a given drive number, so you could have 4 35-40 track
file systems on a single 720K disk.  For instance, you could have drives
0 and 1 as physical drive 0, side 0; drive 1, side 0 in a 2 drive
system.  Drives 2 and 3 are physical drive 0, side 1, drive 1, side 1. 
This is how I have my drives now.  Then drive 4 could be physical drive
0, side 0, track 40+, etc.  I guess that calls for some investigation in
Disk BASIC Unravelled.

Finally, Chuck Youse has designed a high density disk controller for the
CoCo.  At this point I think he's only got drivers for (Nitr)OS-9.  But
the possibility of using 1.44M floppy disks on the CoCo is distinct.

JCE
> Cheers.
>
> Phill.
>